Figure 1. In vivo detection of orthotopically injected human tumor cells labeled with the luciferase reporter gene. A) Tumor growth of liposarcoma orthotopically injected into the retroperitoneal fat pad was monitored and quantified according to bioluminescence from labeled cells. The red line represents photon emission from mice injected with cells of the angiogenic clone 9, whereas the blue line represents that of mice injected with cells of the nonangiogenic dormant clone 4. Data are presented as mean ± SE. Eight mice were used per group (total of 16 mice per experiment) B) Representative mice that were orthotopically injected with cells from clone 9 (left) or clone 4 (right) at day 27 after injection. The gray photographic images of the mice and bioluminescence color images were superimposed. C) The presence of tumors was confirmed by histological analysis according to H&E staining (original magnification x100).